Water-Repellent Perovskites Induced by a Blend of Organic Halide Salts for Efficient and Stable Solar Cells

Concentration Dependent Modulation in Optoelectronic Traits of Self-Collated CsPbBr3 Perovskites

Self-collation of perovskite nanocrystals into superstructures of larger length scales has been growing in research interest due to their dramatically enhanced performance in various nano-devices, modulating their optical and electrical traits. Herein, the unique concentration-dependent self-assembly of phenethylamine (PEA)-capped CsPbBr3 (PCPB) perovskites spanning a size range of nano to micron level without structural phase alteration is infered. By optimizing various synthetic parameters like PEA amount, and solvents, the self-coalescence in PCPB crystal growth is controlled. Furthermore, the highest-concentrated PCPB (C5) has improved the charge transfer (CT) efficiency to 1,4-Napthoquinone (NPQ), corroborated with stronger binding between C5 and NPQ, compared to the lowest-concentrated PCPB (C1). Incorporating NPQ into such concentration-dependent PCPB enhances their local conductance unveiling the CT-induced current rise, while the detrimental insulating property of PEA molecules reduces the conductance in C5 compared to C1. These outcomes offer a foundation for tailoring the properties of self-assembled perovskites for optoelectronic devices and energy conversion technologies.

Multifunctional Thiophene Cascading SnO2/Perovskite Interfaces for Efficient and Stable MAPbI3 Photovoltaics

The power conversion efficiency (PCE) and stability of n-i-p perovskite solar cells (PSCs) are significantly affected by inherent defects of SnO2 and perovskite layers. In this work, we incorporate 2-bromo-3-thiophenic acid (BrThCOOH) as a multifunctional passivant to simultaneously passivate the defects of SnO2 surface and perovskite layer. BrThCOOH permeates evenly into the MAPbI3 and coordinates with Pb2+ and iodine vacancies (VI+) to reduce surface defect density and inhibit the decomposition of MAPbI3. Carboxylic acid effectively passives the oxygen vacancy on the surface of SnO2 through coordination bonds, reducing the probability of electron capture by SnO2 surface defects, thus contributing to electron transport in device. The interaction of BrThCOOH with MAPbI3 and SnO2 surfaces leads to an upward shift in energy levels, reducing energy loss during charge migration. The optimal MAPbI3 device with BrThCOOH-modified SnO2 (T-SnO2) reveals an improved PCE of 21.12%, much higher than that of the control one (19.12%). The hydrophobicity of BrThCOOH-modified MAPbI3 is also improved, which is beneficial to the durability of the device. After 100 h of storage in the environment, the generated PSCs maintain their initial PCE of 75%, demonstrating excellent long-term stability without any encapsulation.

Lead immobilization for environmentally sustainable perovskite solar cells

Lead halide perovskites are promising semiconducting materials for solar energy harvesting. However, the presence of heavy-metal lead ions is problematic when considering potential harmful leakage into the environment from broken cells and also from a public acceptance point of view. Moreover, strict legislation on the use of lead around the world has driven innovation in the development of strategies for recycling end-of-life products by means of environmentally friendly and cost-effective routes. Lead immobilization is a strategy to transform water-soluble lead ions into insoluble, nonbioavailable and nontransportable forms over large pH and temperature ranges and to suppress lead leakage if the devices are damaged. An ideal methodology should ensure sufficient lead-chelating capability without substantially influencing the device performance, production cost and recycling. Here we analyse chemical approaches to immobilize Pb2+ from perovskite solar cells, such as grain isolation, lead complexation, structure integration and adsorption of leaked lead, based on their feasibility to suppress lead leakage to a minimal level. We highlight the need for a standard lead-leakage test and related mathematical model to be established for the reliable evaluation of the potential environmental risk of perovskite optoelectronics.